Catalytic converter apparatus

ABSTRACT

A catalytic converter apparatus for use in an exhaust system of an internal combustion engine includes a housing having a gas inlet and a gas outlet, and at least one catalytic substrate element disposed in the housing. The at least one substrate element is divided into a plurality of zones or sections, the zones at least partially separated from one another to inhibit heat flow. The zones can be at least partially separated with walls. The walls can include insulating material for reducing the mobility of heat radially outwardly. Each of the zones defines a generally separate flow passage connecting the inlet and outlet in fluid communication. The apparatus can heat more rapidly from a cold start compared with conventional catalytic converters.

CROSS-REFERENCE TO PENDING APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 14/555,123 filed Nov. 26, 2014 entitled “CatalyticConverter Apparatus” which is a continuation application of U.S. patentapplication Ser. No. 14/080,483 filed Nov. 14, 2013 which is acontinuation of U.S. patent application Ser. No. 13/644,859 filed Oct.4, 2012, now abandoned, which is a divisional application of U.S. patentapplication Ser. No. 12/548,676 filed Aug. 27, 2009, now U.S. Pat. No.8,309,032, which claims the benefit of U.S. Provisional Application No.61/092,110 filed Aug. 27, 2008, which is hereby incorporated byreference in its entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

This specification relates to a catalytic converter apparatus for aninternal combustion engine.

2. Prior Art

The following paragraphs are not an admission that anything discussed inthem is prior art or part of the knowledge of persons skilled in theart.

U.S. Pat. No. 4,394,351 to Gast discloses a dualmonolith catalyticconverter having upstream and downstream located substrates and aconfiguration such that the exhaust gas flow is non-uniformlydistributed across the upstream frontal areas of each of the substratesand concentrated centrally of such frontal areas. The converter furtherhas a chamber located between said substrates. An air distribution tubehaving an open end adapted to be connected to the pulsed air supplyextends through and across the chamber substantially normal to theexhaust gas flowing between the substrates and terminates with a closedend. The tube within the chamber has a plurality of holes which aresized and spaced along the tube to non-uniformly distribute the pulsedair supply throughout the chamber in a manner to provide a resultant airflow distribution conforming with the non-uniform distribution ofexhaust gas. Flow dividers are spaced along the tube and extendsubstantially parallel to the flow of exhaust gas between the substratesin a manner to partition the chamber into a plurality of discretechannels each open to selected ones of the holes to receive one portiononly of the non-uniform distribution of the pulsed air supply and oneportion only of the non-uniformly distributed exhaust gas whereby thenon-uniform air flow distribution is maintained between the channelswhile the exhaust gas is flowing between the substrates to prevent theexhaust gas from entering the downstream substrate with an improper mixof pulsed air so that the conversion efficiency of the downstreamsubstrate is maximized

U.S. Pat. No. 5,578,277 to White et al. discloses a modular catalyticconverter and muffler used to purify exhaust from a relatively largediesel engine. The device includes various structural components thatare mounted in the exhaust flow path within a housing having an inletand an outlet. A plate mounted within the housing divides the housinginto an inlet chamber and an outlet chamber. A plurality of catalyticconverter sub-cans are mounted across the plate between the inletchamber and the outlet chamber. A flow distributor is mounted within thehousing upstream of the catalytic converter sub-cans. The flowdistributor divides and directs a portion of the exhaust to each of thecatalytic converter sub-cans. Some muffler structure is mounted withinthe housing between the catalytic converter sub-cans and the outlet inorder to attenuate noise in the exhaust.

U.S. Pat. No. 7,210,287 to Bolander et al. discloses a method ofreducing exhaust emission from a catalytic converter apparatus of avehicle, the apparatus including at least one catalytic converter, eachof the at least one catalytic converter having a catalyst brickpositioned within a predefined length of the vehicle. The methodincludes directing exhaust to pass more than once through the predefinedlength through at least one of the at least one catalyst brick. Theconverter apparatus can accelerate catalyst conversion reactions andthus accelerate converter system light-off.

SUMMARY OF THE INVENTION

In an aspect of this specification, a catalytic converter apparatus foruse in an exhaust system of an internal combustion engine can include: ahousing, the housing including a gas inlet and a gas outlet; and atleast one substrate element arranged in the housing, the at least onesubstrate element including catalytic material, the at least onesubstrate element divided into a plurality of zones, each of the zonesdefining a generally separate flow passage connecting the inlet and theoutlet in fluid communication.

The apparatus can further include at least one wall at least partiallyseparating the plurality of zones. The at least one wall can includeinsulating material for inhibiting heat flow between the zones.Thickness of the insulating material between the zones can be varied.The insulating material can have a thickness between the zones of lessthan 10 mm. The insulating material can include ceramic fiber material.

The at least one wall can separate the zones so as to be generallyimpervious to gas flow between adjacent zones. The at least one wall canseparate the zones along substantially an entire length of the zones ina direction extending from the inlet to the outlet. The zones caninclude a central zone and at least one radial zone. The at least onewall separating the central substrate zone from the at least one radialzone can include at least one connecting portion.

The at least one substrate element can substantially fill the housing ina radial dimension perpendicular to a direction of gas flow extendingfrom the inlet to the outlet. The zones can be arranged generally inparallel in a direction of gas flow extending from the inlet to theoutlet. Cross-sectional areas of the zones in a plane perpendicular to adirection of gas flow extending from the inlet to the outlet can bevaried. Zones centrally located can have a larger cross-sectional areathan zones peripherally located.

Each of the zones can be of like cross-sectional shape in a planeorthogonal to a direction of gas flow. The shape can be selected fromthe group consisting of trapezoids, rectangles, squares, triangles,hexagons and circles.

Loadings of the catalytic material in the zones can be varied. Forexample, loadings of the catalytic material in zones centrally locatedcan be greater than loadings of the catalytic material in zonesperipherally located. Similarly, catalytic surface areas of the zones ofthe at least one substrate can be varied. For example, catalytic surfaceareas of the zones centrally located can be greater than catalyticsurface areas of the zones peripherally located.

In an aspect of this specification, a catalytic converter apparatus foruse in an exhaust system of an internal combustion engine can include: ahousing, the housing including a gas inlet and a gas outlet; at leastone substrate element arranged in the housing, the at least onesubstrate element including catalytic material, the at least onesubstrate element divided into a plurality of zones, the zones arrangedgenerally in parallel in a direction of gas flow extending from theinlet to the outlet, each of the zones defining a generally separateflow passage connecting the inlet and the outlet in fluid communication;and at least one wall at least partially separating the plurality ofzones, the at least one wall separating the zones so as to be generallyimpervious to gas flow between adjacent zones, the at least one wallincluding insulating material.

A method of reducing emissions from an internal combustion engine caninclude providing the catalytic converter apparatus as described aboveand placing the inlet of the apparatus in fluid communication with anexhaust gas stream of the engine.

In an aspect of this specification, a method of reducing emissions froman internal combustion engine can include: delivering an exhaust gasstream from the internal combustion engine to at least one substrateelement having a plurality of zones, the at least one substrate elementincluding catalytic material located therein, the zones at leastpartially separated from one another so that heat flow between the zonesis at least partially inhibited by the insulating material, each of thezones defining a generally separate flow passage; passing the streamthrough the plurality of zones thereby causing the stream to separateinto a plurality of individual streams, the individual streams reactingwith the catalytic material of the substrate element to form a pluralityof treated streams; and expelling the treated streams.

Other aspects and features of the teachings disclosed herein will becomeapparent, to those ordinarily skilled in the art, upon review of thefollowing description of the specific examples of the specification.

BRIEF DESCRIPTION OF THE DRAWINGS

The skilled person in the art will understand that the drawings,described below, are for illustration purposes only. The drawings arenot intended to limit the scope of the applicant's teachings in any way.

FIG. 1A is a side cutaway view of an apparatus;

FIG. 1B is a sectional view of the apparatus of FIG. 1A;

FIG. 1C is a perspective cutaway view of the apparatus of FIG. 1A;

FIG. 2A is a side cutaway view of an apparatus;

FIG. 2B is a sectional view of the apparatus of FIG. 2A;

FIG. 2C is a perspective cutaway view of the apparatus of FIG. 2A;

FIG. 3A is a side cutaway view of an apparatus;

FIG. 3B is a sectional view of the apparatus of FIG. 3A;

FIG. 3C is a perspective cutaway view of the apparatus of FIG. 3A;

FIG. 4A is a side cutaway view of an apparatus;

FIG. 4B is a sectional view of the apparatus of FIG. 4A;

FIG. 4C is a perspective cutaway view of the apparatus of FIG. 4A;

FIG. 5A is a side cutaway view of an apparatus;

FIG. 5B is a sectional view of the apparatus of FIG. 5A;

FIG. 5C is a perspective cutaway view of the apparatus of FIG. 5A;

FIGS. 6 to 9 are sectional views of other apparatuses;

FIG. 10 is a graph showing testing results; and

FIG. 11 is another graph showing testing results.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Various apparatuses or methods will be described below to provide anexample of embodiment of each claimed invention. No embodiment describedbelow limits any claimed invention and any claimed invention may coverapparatuses or methods that are not described below. One or moreinventions may reside in a combination or sub-combination of theapparatus sections or method steps described below or in other parts ofthis document. The claimed inventions are not limited to apparatuses ormethods having all of the features of any one apparatus or methoddescribed below or to features common to multiple or all of theapparatuses described below. It is possible that an apparatus or methoddescribed below is not an embodiment of any claimed invention. Theapplicant(s), inventor(s) and/or owner(s) reserve all rights in anyinvention disclosed in an apparatus or method described below that isnot claimed in this document and do not abandon, disclaim or dedicate tothe public any such invention by its disclosure in this document.

Catalytic converters are widely used in motor vehicle exhaust systems toreduce the toxicity of emissions. In a typical catalytic converter, asubstrate can take the form of a cylinder-shaped porous unitarystructure that is coated with catalytic materials. A typical convertercan contain two separate catalyst-coated stages: the first catalyststage for reduction of NOx, and the second stage for oxidation of CO andhydrocarbons. The substrate is usually formed of porous ceramicmaterial, or in some cases, stainless steel. From a cold start,catalytic material in the catalytic converter heats up as emission gasespass therethrough, the conversion of exhaust gases is accelerated andemission levels decrease.

Conventional catalytic converters typically only work efficiently oncethe substrate has reached relatively high operating temperatures.Operating temperatures can take several minutes to attain after enginestartup. In some examples, catalytic converters consisting of a unitaryceramic catalyst substrate can have a “light-off” temperature (thetemperature at which the catalytic converter is converting at 50%efficiency) of about 300° C., and an operating temperature of about 500°C. to 600° C. During the time it takes for the substrate to reachoperating temperatures, untreated toxic components are being emittedfrom the exhaust system.

Applicant's teachings relate to a catalytic converter apparatus havingat least one substrate element that is divided or separated into aplurality of zones or sections. The zones can be at least partiallyseparated from one another by walls to inhibit heat flow between thezones. The walls can include insulating material for reducing themobility of heat radially outwardly. The zones can heat up generallyindependently of one another, enabling relatively rapid heating. Rapidheating can allow for a reduction in the amount of time required toachieve operating temperatures at which efficient conversion takesplace. Use of the apparatus therefore can reduce the amount of untreatedtoxic components being emitted from the exhaust system during ascompared with conventional catalytic converters with unitary ormonolithic substrates. Furthermore, the walls can provide for betterheat retention within the apparatus, which can serve to maintain anelevated temperature during shutoff or engine idling. Moreover, in someexamples, apparatuses in accordance with the Applicant's teachings canbe more resilient to mechanical and thermal stress as compared withconventional catalytic converters with unitary or monolithic substrates.

Referring to FIGS. 1A, 1B and 1C, an example of a catalytic converterapparatus is shown generally at 100. The apparatus 100 is for use in anexhaust system of an internal combustion engine (not shown). Theapparatus 100 includes a housing 102. The housing 102 can be, forexample but not limited to, roughly cylindrical, having oval, circularor elliptical cross-sectional shapes. Various shapes and dimensions ofthe housing 102 are possible. The housing 102 includes a gas inlet 104,and a gas outlet 106 spaced apart from the inlet 104.

The apparatus 100 includes at least one substrate element 108 arrangedin the housing 102. The substrate element 108 is divided or separatedinto zones or sections 108 a, 108 b. The zones 108 a, 108 b can belaterally arranged with each defining a generally separate chamber orflow passage connecting the inlet 104 and the outlet 106 in fluidcommunication.

The zones 108 a, 108 b can be at least partially separated from oneanother by at least one wall 110. The walls 110 can extend alongsubstantially an entire length of the zones 108 a, 108 b in a directionextending from the inlet 104 to the outlet 106. The walls 110 canseparate each of the zones 108 a, 108 b from one another so as to begenerally impervious to gas flow between the zones 108 a, 108 b. Atleast a portion of the walls 110 can include insulating material, asdiscussed in further detail below.

The at least one substrate element 108 can be formed from a generallyporous ceramic, or stainless steel structure, including ceramicformulations and stainless steel materials that are used in existingcatalytic converters. The substrate element 108 includes catalyticmaterial for converting exhaust gases. The catalytic material can be anysuitable material operable to conduct the oxidation/reduction reactionsdesirable to convert the vehicle emissions. In some examples, wherethree-way conversion is desired, each of the zones 108 a, 108 b cancomprise two separate catalyst-coated stages arranged in series (notshown).

The zones 108 a, 108 b can substantially fill the housing 102 in aradial or lateral dimension relative to an axis of gas flow from theinlet 104 to the outlet 106. The zones 108 a, 108 b can be arrangedgenerally in parallel in a direction extending from the inlet 104 to theoutlet 106.

The zones 108 a, 108 b can be at least partially separated from oneanother with walls 110, reducing heat mobility within the apparatus 100.As illustrated in this particular example, the at least one wall 110 canbe separated into wall sections 110 a, 110 b, 110 c, 110 d by connectingportions 114. The connecting portions 114 provide structural supportbetween the zones 108 a, 108 b, which can aid manufacturing.

Specifically, a unitary substrate element including zones 108 a, 108 bcan be formed by an extrusion process, with voids for each of the wall110 a, 110 b, 110 c, 110 d. The voids can be subsequently injectionmolded with insulating material to form the walls 110 a, 110 b, 110 c,110 d. Subsequent to extruding the zones 108 a, 108 b and prior toinjection molding the walls 110 a, 110 b, 110 c, 110 d, the connectingportions 114 can provide structural support between the zones 108 a, 108b.

The walls 110 can be formed partially or entirely of insulatingmaterial. In some particular examples, walls 110 can at least partiallyinclude a ceramic fiber insulating material, for example but not limitedto, FIBERFRAX XFP™ materials (Unifrax Corporation of Niagara Falls,N.Y.). In some other particular examples, walls 110 can at leastpartially include moldable cements, for example but not limited toFIBERFRAX LDS MOLDABLE™ materials (Unifrax Corporation of Niagara Falls,N.Y.). In other examples, walls 110 can at least partially include otherinsulating materials such as aerogels or nanogels, glass wool, etc.

By incorporating the walls 110 with insulating materials between thezones 108 a, 108 b, the apparatus 100 can be more resilient tomechanical and thermal stress. Insulating materials can typically allowfor an amount of compression and can therefore accommodate thermalexpansion of each of the zones 108 a, 108 b. Insulating materials canalso provide for improved mechanical flexibility.

Optionally, referring to FIG. 1B, an insulating layer 112 can bearranged between the zone 108 b and the housing 102. The insulatinglayer 112 can minimize heat loss outwardly from the zone 108 b and thehousing 102 so that the zones 108 a, 108 b retain heat, further reducingthe amount of time required to achieve operating temperatures at whichefficient conversion takes place.

In use, the apparatus 100 can be implemented to reduce emissions from aninternal combustion engine (not shown). In particular, the inlet 104 canbe placed in fluid communication with an exhaust gas stream of theengine. The exhaust gas stream can be delivered to the zones 108 a, 108b. The stream can be passed through the zones 108 a, 108 b therebycausing the stream to separate into a plurality of individual streams,each individual stream reacting with the catalytic material of the atleast one substrate element to form a treated stream. The treatedstreams can be combined to form an outlet gas stream, and then expelledfrom the outlet 106.

The zones 108 a, 108 b can heat up generally independently of oneanother. Therefore, the apparatus 100 may exhibit enhanced conductiveheating as compared with a unitary or monolithic substrate design, sincethermal energy is transferred separately through the zones 108 a, 108 b.Furthermore, if the zone 108 a heats more quickly than the zone 108 bdue to uneven heat distribution in the exhaust gas stream, e.g., hottertowards the middle of the stream, the higher temperature zone 108 a maybe able to reach light-off sooner to catalyze emissions, even thoughother substrate zones 108 have not reached the light-off temperature.Conversely, during idling, idle gases may cool zone 108 a more quicklythan zone 108 b, so that the zone 108 b retains heat and is able torecover more quickly from a period of idling.

There are three mechanisms of heat transfer between different parts of aconventional catalytic converter apparatus: (i) convection of hot gasinside the substrate; (ii) conduction through the substrate; and (iii)radiation from the substrate. For apparatus 100, the first twomechanisms, convection and conduction, can be obstructed by theintroduction of the walls 110 (disregarding the connecting portions 114,which may allow for some minor heat transfer between the zones 108 a,108 b). The third mechanism, radiation, can be highly dependent ontemperature of the substrate, and can be a significant contributor onlyat high temperatures. For example, at 100° C., loss of heat due toradiation for a substrate material can be estimated to be about 1.4kW/m²s, while at 700° C., loss of heat due to radiation can be estimatedto be about 57 kW/m²s, an increase of a factor of 40. Therefore,introduction of the walls 110 between the zones 108 a, 108 b can impedeheat transfer within the apparatus 100 at lower temperatures, whereas athigher temperatures, increasing participation of radiation can bypassthe effect of the insulating materials and increase heat mobilitybetween the zones 108 a, 108 b, preventing the zones 108 a, 108 b fromoverheating.

However, it should be appreciated that a single layer of insulationapplied externally to the substrate zones (i.e. 112) cannot achieve thesame effect as incorporating layers of the insulating material in walls110 between the zones 108 a, 108 b. Solid mater is conductive, whereasmost gases including air are poor conductors and good insulators. Mosteffective insulating materials are porous, and conductive heat transferis largely reduced by the presence of the air-filled spaces (having lowthermal conductivity) rather than by the material itself. As thetemperature of the insulating material increases, its ability to conductheat increases as well. Trapped air becomes a better conductor due torapid movement of air molecules at higher temperatures. In addition, thesolid part of the insulating material itself will start radiating morewith an increase in temperature. Unlike insulation, the zones 108 a, 108b can be generally solid and thus not subject to such substantialchanges in thermal conductivity.

Consequently, it should be appreciated that as temperatures increase theinsulating materials will exhibit a decreased effectiveness at impedingthe mobility of heat within the apparatus 100, which can prevent thezones 108 a, 108 b from overheating. In contrast, a single, relativelythick layer of insulating material can increase the ability of asubstrate zone to retain heat, and thus it can heat up faster, but itcan also decrease its ability to lose heat at high temperature, whichcan lead to overheating.

As an example, the apparatus 100 can have a width dimension of about 12cm and a height dimension of about 8 cm. The dimensions may varydepending on the application. The walls 110 and the insulating materialtherein separating the zones 108 a, 108 b can have a thickness, forexample but not limited to, less than 10 mm, or between 0.1 and 5 mm, orbetween 0.5 and 2 mm. Thickness of the insulating material can be varieddepending on the operating temperature (i.e. thinner for lowertemperature) and properties of the insulating material. The insulatingmaterial in the walls 110 separating the zones 108 a, 108 b can begenerally uniform in thickness.

End surfaces of the walls 110 can serve to obstruct axial gas flow,since at least a portion of the exhaust gas stream entering the inlet104 must divert from its path to enter a respective one of the zones 108a, 108 b. The diversion of at least a portion of the gas stream cancreate a pressure build up and increase turbulence of the gas flow atthe ends of the zones 108 a, 108 b facing in the inlet 104. Increasedturbulence can cause a corresponding increase in temperature of the gasstream, which can enhance the heating of the zones 108 a, 108 b and therate at which operating temperatures are achieved.

However, in cases where an increase in backpressure is to be avoided,the sectional dimensions of the apparatus 100 in a direction orthogonalto gas flow can be decreased in an amount proportional to the amount ofsectional area occupied by the walls 110. For example, referring to FIG.1B, if the walls 110 constitute about 10% of the overall sectional areaof the apparatus 100, then the dimensions of the apparatus 100 can bedecreased by about 10% to offset the backpressure effect of the walls110.

Referring to FIGS. 2A, 2B and 2C, another example of a catalyticconverter apparatus is shown generally at 200. The apparatus 200 issimilar to apparatus 100, with like features identified by likereference numbers. The apparatus 200 includes a housing 202. The housing202 can be roughly cylindrical, having a generally circularcross-sectional shape. The housing 202 includes a gas inlet 204, and agas outlet 206 spaced apart from the inlet 204.

The apparatus 200 includes at least one substrate element 208 arrangedin the housing 202. The substrate element 208 is divided or separatedinto zones or sections 208 a, 208 b, 208 c. The zones 208 a, 208 b, 208c can be laterally or radially arranged with each defining a generallyseparate chamber or flow passage connecting the inlet 204 and the outlet206 in fluid communication. The zones 208 a, 208 b, 208 c cansubstantially fill the housing 202 in a radial dimension relative to anaxis of gas flow from the inlet 204 to the outlet 206. The zones 208 a,208 b can be at least partially separated by a wall 210 a and the zones208 b, 208 c can be at least partially separated by a wall 210 b.Although not shown, the walls 210 a, 210 b can include connectingportions for providing structural support between the zones 208 a, 208b, 208 c (similar to the connecting portions 114 in the apparatus 100).

The zones 208 a, 208 b, 208 c can be separated from one another by thewalls 210 a, 210 b extending along substantially an entire length of thezones 208 a, 208 b, 208 c in a direction extending from the inlet 204 tothe outlet 206. The walls 210 a, 210 b can separate the zones 208 a, 208b, 208 c from one another so as to be generally impervious to gas flowbetween adjacent zones 208 a, 208 b, 208 c.

The walls 210 a, 210 b can include insulating material to reduce heatmobility within the apparatus 200. In some examples, the walls 210 a,210 b can be formed partially of insulating material and can alsoinclude some structure to separate the zones 208 a, 208 b, 208 c anddefine separate flow passages (e.g., relatively thin solid ceramic orstainless steel material). In some other examples, the walls 210 a, 210b can be formed entirely of insulating material.

The insulating material in the walls 210 a, 210 b can be generallyuniform in thickness. Alternatively, the insulating material can bevaried in thickness. For example, where there is a marked uneven heatdistribution of the exhaust gas stream, e.g., the stream is hottertowards the middle, it may be desirable to more heavily insulate thezone 208 c located around the periphery near the housing 202 than thezone 208 a that is centrally located. Thus, wall 210 b can be moreheavily insulated than wall 210 a.

By incorporating the walls 210 a, 210 b with insulating materialsbetween the zones 208 a, 208 b, 208 c, the apparatus 200 can be moreresilient to mechanical and thermal stress. Insulating materials cantypically allow for an amount of compression and can thereforeaccommodate thermal expansion of each of the zones 208 a, 208 b, 208 c.Insulating materials can also provide for improved mechanicalflexibility.

Optionally, referring to FIG. 2B, an insulating layer 212 can bearranged between the zone 208 c and the housing 202. The insulatinglayer 212 can minimize heat loss outwardly from the zone 208 c and thehousing 202 so that the zones 208 a, 208 b, 208 c retain heat, furtherreducing the amount of time required to achieve operating temperaturesat which efficient conversion takes place.

The zones 208 a, 208 b, 208 c can heat up generally independently of oneanother. Therefore, the apparatus 200 may exhibit enhanced conductiveheating as compared with a unitary or monolithic substrate design, sincethermal energy is transferred separately through the zones 208 a, 208 b,208 c. Furthermore, if the zone 208 a heats more quickly than the zones208 b, 208 c due to uneven heat distribution in the exhaust gas stream,e.g., hotter towards the middle of the stream, the higher temperaturezone 208 a may be able to reach light-off sooner to catalyze emissions,even though other zones 208 b, 208 c have not reached the light-offtemperature. Conversely, during idling, idle gases may cool zone 208 amore quickly than zones 208 b, 208 c, so that the zones 208 b, 208 cretain heat and are able to recover more quickly from a period ofidling.

Optionally, the loading of catalytic material can be varied between thezones 208 a, 208 b, 208 c. For example, it may be desirable to producethe apparatus 200 so that the loading of catalytic material in thecentral zone 208 a is greater than that of zone 208 b, and it may befurther desirable to have the loading of catalytic material in zone 208b be greater than that of zone 208 c. In such a configuration, a greaterloading of catalytic material is provided to catalyze emissions in thecentrally located zones, which are typically handling a greater flow ofemissions than the peripherally located zones.

Also optionally, the catalytic surface area can be varied between thezones 208 a, 208 b, 208 c. For example, it may be desirable to producethe apparatus 200 so that the catalytic surface area in the central zone208 a is greater than that of zone 208 b, and it may be furtherdesirable to have the catalytic surface area in zone 208 b be greaterthan that of zone 208 c. In such a configuration, a greater catalyticsurface area is provided to catalyze emissions in the centrally locatedzones, which are typically handling a greater flow of emissions than theperipherally located zones.

Referring to FIGS. 3A, 3B and 3C, another example of a catalyticconverter apparatus is shown generally at 300. The apparatus 300 issimilar to apparatuses 100 and 200, with like features identified bylike reference numbers. The apparatus 300 includes a housing 302. Thehousing 302 can be roughly cylindrical, having a generally ovalcross-sectional shape. The housing 302 includes a gas inlet 304, and agas outlet 306 spaced apart from the inlet 304.

The apparatus 300 includes at least one substrate element 308 a arrangedin the housing 302. The substrate element 308 is divided or separatedinto zones or sections 308 a, 308 b, 308 c. The zones 308 a, 308 b, 308c can be laterally or arranged with each defining a generally separatechamber or flow passage connecting the inlet 304 and the outlet 306 influid communication. The zones 308 a, 308 b, 308 c can substantiallyfill the housing 302 in a radial dimension relative to an axis of gasflow from the inlet 304 to the outlet 306.

Walls 310 a, 310 b at least partially separate zone 308 a from zones 308b, 308 c. The walls 310 a, 310 b can extend along substantially anentire length of the zones 308 a, 308 b, 308 c in a direction extendingfrom the inlet 304 to the outlet 306. The walls 310 a, 310 b canseparate the zones 308 a, 308 b, 308 c from one another so as to begenerally impervious to gas flow between adjacent zones 308 a, 308 b,308 c.

The walls 310 a, 310 b can include insulating material to reduce heatmobility within the apparatus 300. In some examples, the walls 310 a,310 b can be formed partially of insulating material and can alsoinclude some structure to separate the zones 308 a, 308 b, 308 c anddefine separate flow passages (e.g., relatively thin solid ceramic orstainless steel material). In some other examples, the walls 310 a, 310b can be formed entirely of insulating material.

By incorporating the walls 310 a, 310 b with insulating materialsbetween the zones 308 a, 308 b, 308 c, the apparatus 300 can be moreresilient to mechanical and thermal stress. Insulating materials cantypically allow for an amount of compression and can thereforeaccommodate thermal expansion of each of the zones 308 a, 308 b, 308 c.Insulating materials can also provide for improved mechanicalflexibility.

Optionally, referring to FIG. 3B, an insulating layer 312 can bearranged between the zones 308 b, 308 c and the housing 302. Theinsulating layer 312 can minimize heat loss outwardly from the zone 308c and the housing 302 so that the zones 308 a, 308 b, 308 c retain heat,further reducing the amount of time required to achieve operatingtemperatures at which efficient conversion takes place.

The zones 308 a, 308 b, 308 c can heat up generally independently of oneanother. Therefore, the apparatus 300 may exhibit enhanced conductiveheating as compared with a unitary or monolithic substrate design, sincethermal energy is transferred separately through the zones 308 a, 308 b,308 c. Furthermore, if the zone 308 a heats more quickly than the zones308 b, 308 c due to uneven heat distribution in the exhaust gas stream,e.g., hotter towards the middle of the stream, the higher temperaturezone 308 a may be able to reach light-off sooner to catalyze emissions,even though other zones 308 b, 308 c have not reached the light-offtemperature. Conversely, during idling, idle gases may cool zone 308 amore quickly than zones 308 b, 308 c, so that the zones 308 b, 308 cretain heat and are able to recover more quickly from a period ofidling.

Similar to what was described for apparatus 200, the loading ofcatalytic material can be varied between the zones 308 a, 308 b, 308 c.For example, the apparatus 300 can be prepared so that the loading ofcatalytic material in the central zone 308 a is greater than that ofzone 308 b, and the loading of catalytic material in zone 308 b isgreater than that of zone 308 c.

Referring to FIGS. 4A, 4B and 4C, another example of a catalyticconverter apparatus is shown generally at 400. The apparatus 400 issimilar to apparatuses 100, 200 and 300, with like features identifiedby like reference numbers. The apparatus 400 includes a housing 402. Thehousing 402 can be roughly cylindrical, having a generally ellipticalcross-sectional shape. The housing 402 includes a gas inlet 404, and agas outlet 406 spaced apart from the inlet 404.

The apparatus 400 includes at least one substrate element 408 arrangedin the housing 402. The substrate element 408 is divided or separatedinto zones or sections 408 a, 408 c, 408 d. The zones 408 a, 408 b, 408c, 408 d can be laterally arranged with each defining a generallyseparate chamber or flow passage connecting the inlet 404 and the outlet406 in fluid communication. The zones 408 a, 408 b, 408 b, 408 d cansubstantially fill the housing 402 in a radial dimension relative to anaxis of gas flow from the inlet 404 to the outlet 406.

Walls 410 a, 410 b, 410 c, 410 d at least partially separate the zones408 a, 408 b, 408 c, 408 d. The walls 410 a, 410 b, 410 c, 410 d canextend along substantially an entire length of the zones 408 a, 408 b,408 c, 408 d in a direction extending from the inlet 404 to the outlet406. The walls 410 a, 410 b, 410 c, 410 d can separate the zones 408 a,408 b, 408 c, 408 d from one another so as to be generally impervious togas flow between adjacent zones 408 a, 408 b, 408 c, 408 d.

The walls 410 a, 410 b, 410 c, 410 d can include insulating material toreduce heat mobility within the apparatus 400. In some examples, thewalls 410 a, 410 b, 410 c, 410 d can be formed partially of insulatingmaterial and can also include some structure to separate the zones 408a, 408 b, 408 c, 408 d and define separate flow passages (e.g.,relatively thin solid ceramic or stainless steel material). In someother examples, the walls 410 a, 410 b, 410 c, 410 d can be formedentirely of insulating material.

By incorporating the walls 410 a, 410 b, 410 c, 410 d with insulatingmaterials between the zones 408 a, 408 b, 408 c, 408 d, the apparatus400 can be more resilient to mechanical and thermal stress. Insulatingmaterials can typically allow for an amount of compression and cantherefore accommodate thermal expansion of each of the zones 408 a, 408b, 408 c, 408 d. Insulating materials can also provide for improvedmechanical flexibility.

Optionally, referring to FIG. 4B, an insulating layer 412 can bearranged between the zones 408 d and the housing 402. The insulatinglayer 412 can minimize heat loss outwardly from the zone 408 c and thehousing 402 so that the zones 408 a, 408 b, 408 c, 408 d retain heat,further reducing the amount of time required to achieve operatingtemperatures at which efficient conversion takes place.

The zones 408 a, 408 b, 408 c, 408 d can heat up generally independentlyof one another. Therefore, the apparatus 400 may exhibit enhancedconductive heating as compared with a unitary or monolithic substratedesign, since thermal energy is transferred separately through the zones408 a, 408 b, 408 c, 408 d. Furthermore, if the zone 408 a heats morequickly than the zones 408 b, 408 c, 408 d due to uneven heatdistribution in the exhaust gas stream, e.g., hotter towards the middleof the stream, the higher temperature zone 408 a may be able to reachlight-off sooner to catalyze emissions, even though other zones 408 b,408 c, 408 d have not reached the light-off temperature. Conversely,during idling, idle gases may cool zone 408 a more quickly than zones408 b, 408 c, 408 d so that the zones 408 b, 408 c, 408 d retain heatand are able to recover more quickly from a period of idling.

The average thermal conductivity of the combination of zones 408 a, 408b, 408 c, 408 d and walls 410 a, 410 b, 410 c, 410 d can be determinedby the length of the path traveled through each of the constituents.Therefore, for some particular examples, it is effective to position thewalls in generally parallel layers corresponding with the overallcross-sectional shape of the housing. As illustrated, and withparticular reference to FIG. 4B, with a housing 402 having an ellipticalcross-sectional shape, the apparatus 400 can comprise a central zone 408a, and concentrically arranged radial zones 408 b, 408 c, 408 d. Thewalls 410 a, 410 b, 410 c, 410 d are concentric and are roughly inparallel with the shape of the housing 402. This configuration canminimize the number of zones and the amount of insulating materials usedin the walls. Furthermore, the radially extending walls 410 a can beincluded to separate each of the radial zones 408 b, 408 c, 408 d intoroughly complementary half portions, which can simplify assembly of theapparatus 400.

Referring to FIGS. 5A, 5B and 5C, another example of a catalyticconverter apparatus is shown generally at 500. The apparatus 500 issimilar to apparatuses 100, 200, 300 and 400, with like featuresidentified by like reference numbers. The apparatus 500 includes ahousing 502. The housing 502 can be, for example but not limited to,roughly cylindrical, having a circular cross-sectional shape. Thehousing 502 includes a gas inlet 504, and a gas outlet 506 spaced apartfrom the inlet 504.

The apparatus 500 includes at least one substrate element arranged inthe housing 502 and divided or separated into a plurality of zones orsections 508. Each of the zones 508 can consist of a unitary substrateelement. The zones 508 can be laterally arranged with each defining agenerally separate chamber or flow passage connecting the inlet 504 andthe outlet 506 in fluid communication. The zones 508 can substantiallyfill the housing 502 in a radial dimension relative to an axis of gasflow from the inlet 504 to the outlet 506. In some examples, theapparatus 500 can include at least twenty five substrate zones 508. Insome examples, the apparatus 500 can include at least one hundredsubstrate zones 508.

Walls 510 at least partially separate the zones 508. The walls 510 canextend along substantially an entire length of the zones 508, in adirection extending from the inlet 504 to the outlet 506. The walls 510can separate the zones 508 from one another so as to be generallyimpervious to gas flow between adjacent zones 508.

The walls 510 can include insulating material to reduce heat mobilitywithin the apparatus 500. In some examples, the walls 510 can be formedpartially of insulating material and can also include some structure toseparate the zones 508 and define separate flow passages (e.g.,relatively thin solid ceramic or stainless steel material). In someother examples, the walls 510 can be formed entirely of insulatingmaterial.

By incorporating the walls 510 with insulating materials between thezones 508, the apparatus 500 can be more resilient to mechanical andthermal stress. Insulating materials can typically allow for an amountof compression and can therefore accommodate thermal expansion of eachof the zones 508. Insulating materials can also provide for improvedmechanical flexibility.

Optionally, referring to FIG. 5B, an insulating layer 512 can bearranged between the zones 508 and the housing 502. The insulating layer512 can minimize heat loss outwardly from the zones 508 and the housing502 so that the zones 508 retain heat, further reducing the amount oftime required to achieve operating temperatures at which efficientconversion takes place.

The zones 508 can heat up generally independently of one another.Therefore, the apparatus 500 may exhibit enhanced conductive heating ascompared with a unitary or monolithic substrate design, since thermalenergy is transferred separately through the zones 508.

Referring to FIGS. 6, 7, 8 and 9, the number, dimension and shape ofeach of the zones can vary, and can be optimized for a given exhaustsystem. Example apparatuses 600, 700, 800 and 900 are similar toapparatuses 100, 200, 300, 400 and 500, with like features identified bylike reference numbers.

In some examples, each of the zones can be of like cross-sectional shapein a plane orthogonal to a direction of gas flow, with the shapeselected from squares (see FIG. 5B), triangles (see FIG. 6), circles(see FIG. 7), hexagons (see FIG. 8), rectangles (FIG. 9), trapezoids,etc. Other shapes and various combinations thereof of the zones and thehousing are possible.

As illustrated in FIGS. 5B, 6 and 8, the cross-sectional areas of thezones 508, 608, 808 in a plane orthogonal to a direction of gas flow canbe generally uniform. However, referring to FIGS. 1B, 2B, 3B, 4B, 7 and9, the cross-sectional areas of the zones 108, 208, 308, 408, 708 and908 in a plane orthogonal to a direction of gas flow can be varied. Forexample, referring to FIGS. 7 and 9, zones 708 a, 908 a centrallylocated can have a larger cross-sectional area than zones 708 b, 908 bperipherally located. This may be desirable, for example, where there isa marked uneven heat distribution of the exhaust gas stream, e.g., thestream is hotter towards the middle, and the heating enhancementprovided by the plurality of zones 708, 908 is more critical in areasaround the periphery near the housing 702, 902.

The apparatuses disclosed herein can be designed and produced to be ofsimilar dimensions to conventional catalytic converters, and thusinstallable with existing exhaust systems as a retrofit. Variousgeometries are possible so that the apparatus disclosed herein arecompatible with a variety of gasoline or diesel internal combustionengines, and can be used in the exhaust systems of a variety of motorvehicles, for example but not limited to, automobiles, light trucks,heavy trucks, buses, tractors, forklifts and other industrial machinery,motorcycles, etc.

Reference is now made to the following examples, which are intended tobe illustrative but non-limiting.

Example 1

Testing using prototype catalytic converter apparatuses was conducted. Acommercially available catalytic converter (made by Applied Ceramics,Inc. of Atlanta, Ga.) was provided with dimensions of 3.15×4.75×2.5inches, and with a precious metal loading of 20 g/cf. Three prototypecatalytic converter apparatuses were prepared generally to resemble theexample apparatus 100. Prototype 1 had dimensions of 3.15×4.75×2.25inches, and a precious metal loading of 20 g/cf. Prototype 2 haddimensions of 3.15×4.75×2.25 inches, and a precious metal loading of 17g/cf. Prototype 3 had dimensions of 3.15×4.75×2.25 inches, and aprecious metal loading of 14 g/cf. Each prototype included FIBERFRAX LDSMOLDABLE™ materials as the wall separating zones of the substrateelement, with a thickness of about 0.16 cm.

A 2009 TOYOTA COROLLA™ vehicle was equipped with the commercialcatalytic converter and the prototype apparatuses. Third partyindependent testing was conducted in accordance with the United StatesEnvironmental Protection Agency's US06 testing procedure. The vehiclewas subjected to the driving cycle and emissions for each of the coldstart, transition and warm start phases were collected, and averageemissions were measured. The emission results are provided below inTable 1. The testing demonstrated good results for the prototypeapparatuses, even with reduced precious metal loadings.

TABLE 1 Average emission results. Emissions by type (grams per mile) CONOx HC Commercial 2.623 0.608 0.065 Prototype 1 1.344 0.520 0.064Prototype 2 1.533 0.394 0.058 Prototype 3 1.816 0.578 0.068

Example 2

Testing using a prototype catalytic converter apparatus was conducted.Two aftermarket catalytic converters (MAGNAFLOW™ OBD-II CatalyticConverter, MagnaFlow Performance Exhaust of Rancho Santa Margarita,Calif.) were provided, each with a two-stage substrate approximately 100mm long and 125×80 mm oval/ice rink shape. One of the converters wasaltered to resemble example apparatus 500.

To prepare the prototype apparatus, the substrate element was removedfrom the housing and sliced longitudinally into a plurality of zones orsections, each zone having approximately 10 mm by 10 mm squarecross-section in a plane orthogonal to a direction of gas flow. Eachzone was wrapped with FIBERFRAX LDS MOLDABLE™ insulating material. Thewrapped zones were then bundled together and wrapped with an additionalFIBERFRAX™ insulating layer, and inserted back into the housing. Thethickness of the insulating material separating each zone from anadjacent zone was roughly 1 mm. The original steel housing was used, sosome of the volume of the zones (roughly 10-15%) had to be removed toaccount for the thickness of the insulating material, resulting inreduced overall performance due to smaller amount of catalytic material.

A 1986 GMC C3500 SIERRA™ vehicle was equipped with the regular catalyticconverter and with the prototype apparatus. Both catalytic converterswere fitted with a thermocouple in a central position within the housingto measure the internal temperature. The vehicle was started from a coldstart. The engine was accelerated on a dynamometer and kept at aconstant speed of 40 km/h to maintain about 2,000 rpm for the durationof the test procedure. Referring to FIG. 10, the prototype apparatus,denoted by curve line “A”, exhibited a reduced heat up time incomparison to the regular catalytic converter, denoted by line “B”.

Emission measurements were performed at an Ontario Drive Clean Programcertified facility. The vehicle was subjected a standard test using botha standard catalytic converter and the prototype apparatus. The vehiclewas kept idling for approximately 10 minutes, and then emissions wererecorded for 40 km/h speeds using a dynamometer and curb idle speeds.The emission results are provided in Table 2 below. Relatively poorhydrocarbon and carbon monoxide results suggest that the temperaturemeasuring probes may have significantly damaged the catalytic materials,especially the oxidizing portions of the substrates.

TABLE 2 Emission results for a prototype using a standard emissions testCommercial Prototype Emissions type 40 km/h Curb idle 40 km/h Curb idlehydrocarbons (ppm) 60 54 81 107 carbon monoxide (%) 0.04 0.00 0.15 0.03NO (ppm) 1386 N/A 936 N/A

Referring to new FIG. 11, the vehicle was also subjected to a real-timeemissions test. Emissions were recorded every 10 to 15 seconds over a 4minute period. Although there is data scatter, the prototype apparatusappears to achieve operating temperature sooner than the standard,non-modified catalytic converter. Note that ambient temperature duringthis test was relatively low (about 5° C.), resulting in relatively slowheat up times for both catalytic converters.

Example 3

Another prototype catalytic converter was prepared by modifying astandard catalytic converter from a VOLKSWAGEN JETTA™. The catalyticconverter was altered to resemble example apparatus 500. To prepare theprototype apparatus, the standard catalytic converter was disassembledby cutting the stainless steel housing, removing the monolithicsubstrate element, and slicing the substrate longitudinally into aplurality of zones or sections, each zone having approximately 10 mm by10 mm square cross-section in a plane orthogonal to a direction of gasflow. FIBERFRAX LDS MOLDABLE™ material was applied in relatively thinlayers to surfaces of each of the zones. The zones were reassembled in asteel housing having a slightly larger size than that of the original,thus allowing for the thickness of the insulating material so that noremoval of catalytic material was required. The thickness of theinsulating material separating each zone from an adjacent zone wasroughly 2 mm.

Emission measurements were performed at an Ontario Drive Clean Programcertified facility. A 2001 VOLKSWAGEN JETTA™ vehicle was subjected astandard test using both a standard catalytic converter and theprototype apparatus. The vehicle was kept idling for approximately 5 to10 minutes, and then emissions were recorded for 40 km/h speeds using adynamometer and curb idle speeds. The emission results are provided inTable 3 below.

TABLE 3 Emission results using a standard emissions test StandardPrototype Emissions type 40 km/h Curb idle 40 km/h Curb idlehydrocarbons (ppm) 17 17 7 5 carbon monoxide (%) 0.00 0.01 0.03 0.00 NO(ppm) 41 N/A 0 N/A

Example 4

Two MAGNAFLOW™ 94306 catalytic converters were provided. One of theconverters was altered to generally resemble example apparatus 500. Toprepare the prototype apparatus, the substrate element was removed fromthe housing and sliced longitudinally into a plurality of zones orsections, each zone having approximately 10 mm by 10 mm squarecross-section in a plane orthogonal to a direction of gas flow. Eachzone was insulated with a combination of FIBERFRAX XFP™ paper andFIBERFRAX LDS MOLDABLE™ cement materials. The FIBERFRAX XFP™ paper wasthe primary insulator, while the FIBERFRAX LDS MOLDABLE™ cement wasapplied in a thin layer to glue the zones and the FIBERFRAX XFP™ papertogether. The zones were bundled together and inserted back into thehousing. The original steel housing was used, so some of the volume ofthe zones (roughly 10-15%) was removed to account for the thickness ofthe insulating material, resulting in reduced overall performance due tosmaller amount of catalytic material. The thickness of the insulatingmaterial separating each zone from an adjacent zone was roughly 2 mm.

A 1991 PONTIAC GRAND PRIX™ vehicle was equipped with the unmodifiedstandard catalytic converter and with the modified prototype apparatus.Third party independent testing was conducted in accordance with theUnited States Environmental Protection Agency's FTP-75 driving cycle.The vehicle was subjected to the driving cycle and average emissions foreach part of the cycle were recorded. The emission results for the cold,transient and hot phases, respectively, are provided below in Tables 4,5 and 6.

TABLE 4 Cold start phase emission results Commercial Prototype Emissionstype 40 km/h Curb idle 40 km/h Curb idle hydrocarbons (ppm) 58 50 53 40carbon monoxide (%) 0.05 0.02 0.03 0.01 NO (ppm) 254 N/A 186 N/A

TABLE 5 Transient phase emission results Commercial Prototype Emissionstype 40 km/h Curb idle 40 km/h Curb idle hydrocarbons (ppm) 57 81 21 18carbon monoxide (%) 0.06 0.03 0.01 0.01 NO (ppm) 79 N/A 6 N/A

TABLE 6 Hot start phase emission results Commercial Prototype Emissionstype 40 km/h Curb idle 40 km/h Curb idle hydrocarbons (ppm) 0 0 0 0carbon monoxide (%) 0.00 0.00 0.00 0.00 NO (ppm) 0 N/A 0 N/A

While the applicant's teachings are described in conjunction withvarious embodiments, it is not intended that the applicant's teachingsbe limited to such embodiments. The applicant's teachings encompassvarious alternatives, modifications, and equivalents, as will beappreciated by those of skill in the art.

What is claimed is:
 1. A catalytic converter apparatus for use in anexhaust system of an internal combustion engine, the apparatuscomprising: a housing including a gas inlet and a gas outlet; asubstrate element arranged in the housing, the substrate elementcarrying catalytic material and defining a plurality of zones, each ofthe zones defining a generally separate flow passage connecting theinlet and the outlet in fluid communication; and at least one wall atleast partially separating the zones from one another, the at least onewall being adapted to inhibit heat flow between the zones and beinggenerally impervious to gas flow between the zones, wherein the at leastone wall is tubular; wherein each of the zones is a honeycomb substrate,the substrate element substantially fills the housing in a radialdimension perpendicular to a direction of gas flow extending from theinlet to the outlet, and the substrate has a pair of ends, each endhaving a surface and defining, in combination with the housing, a voidthat spans the entirety of the surface.
 2. The apparatus of claim 1,wherein the zones comprise a central zone and a radial zone.
 3. Theapparatus of claim 2, wherein the housing has an inlet cone defining theinlet and an outlet cone defining the outlet the substrate substantiallyfills the housing, but for the cones, in an axial dimension parallel toa direction of gas flow extending from the inlet to the outlet.
 4. Theapparatus of claim 3, wherein the at least one wall comprisescementitious insulating material.
 5. The apparatus of claim 3, whereinthe insulating material comprises ceramic insulating material.
 6. Theapparatus of claim 3, wherein the at least one wall comprises insulatingmaterial.
 7. The apparatus of claim 3, wherein the at least one walldivides the substrate into the plurality of zones.
 8. The apparatus ofclaim 2, wherein the zones are arranged generally in parallel in adirection of gas flow extending from the inlet to the outlet.
 9. Theapparatus of claim 2, wherein loadings of the catalytic material in thezones is varied.
 10. A method of reducing emissions from an internalcombustion engine having a catalytic converter apparatus as set forth inclaim 1, the method comprising: delivering an exhaust gas stream fromthe internal combustion engine to at least one said substrate elementhaving said plurality of zones, the at least one substrate elementincluding said catalytic material located therein, the zones at leastpartially separated from one another so that heat flow between the zonesis at least partially inhibited by the insulating material, each of thezones defining said generally separate flow passage; passing the streamthrough the plurality of zones thereby causing the stream to separateinto a plurality of individual streams, the individual streams reactingwith the catalytic material of the substrate element to form a pluralityof treated streams; and expelling the treated streams wherein the zonesare defined by a unitary substrate element.